Top 2018 hail events and what can be expected for 2019
Chances are that unless you live in one of the states that constitute “Hail Alley,”––Texas, Oklahoma, Colorado, Kansas, Nebraska, and Wyoming––you don’t pay too much attention to hail.
Well, you’re wrong.
Hail can happen anywhere there are severe thunderstorms. For example, Illinois isn’t on the list yet State Farm ranked them 2nd for most hail damage claims in 2017. Minnesota, Indiana, Missouri, Iowa, also made the list.
Read on for the top 2018 hail events and what to expect in 2019.
Hail by the numbers
In 2018, nearly every state experienced at least one large hailstorm, with the majority of hail events occurring in Hail Alley. The National Weather Service (NWS) reported over 5,000 hail events. Over 4,000 of those reports were of hail greater than 1” in diameter which is the threshold for a severe thunderstorm. Approximately 400 of those reports were of 2” or greater which is the NWS’s threshold for large damaging hail. Finally, there were 14 reports of extremely large damaging hail at over 4” including two over 5”. More on these storms later.
While 2018 met the average annual expected quota of around 5,000 reports, there were a few hail storms that were well above average. Alabama saw a state record-breaking hailstone. Colorado and the Rocky Mountain region experienced two hailstorms which caused over $1B in losses each.
Hail occurs when tiny droplets of water get stuck in the updraft of a thunderstorm above the freezing level. The particles become little stones of ice and if they’re up there for long enough, the stones will stick together to create even larger hailstones. This is why most 3” and nearly all 4-5” hail doesn’t look like one smooth ball of ice.
How is hail forecasted?
Forecasting for hail can be difficult. Atmospheric conditions must be prime for a strong updraft. This includes large instability also known as Convective Available Potential Energy or CAPE. Large hailstone generation almost always requires the updraft to also be rotating. This rotation causes the hailstone to essentially bounce up and down in the clouds along and above the freezing level collecting additional water molecules causing the stone to grow. For an updraft to rotate, forecasters look for winds accelerating and changing direction with height. These rotating updrafts within severe thunderstorms are also known as supercells.
Supercells have an associated mesocyclone and over 30% of these Supercell storms also form strong to destructive tornadoes, but not all tornadoes are caused by Supercells. Some are caused by high wind shear within a quasi-linear convective system such as a squall line. In these cases, damaging hail is less common. However, 2018 was odd in that there were nearly 1,400 reports of hail greater than 2” but only 58 strong tornadoes of EF 2 or greater with the strongest being an EF 3 and only 10 tornadoes with that rating.
EF ratings are based on wind speeds estimated by damage surveys based on the Enhanced Fujita Scale. The only logical explanation for these statistics are that instability, on average, was much greater than wind shear needed to allow the updrafts to rotate. This is likely caused by the transition we experience from ENSO neutral to the current El Niño watch for 2019. Let’s take a closer look at a few of the hail events that stick out the most.
How did hail affect 2018?
The largest hailstones of the year were actually all associated with the same low-pressure system that moved from the Great Plains over to the Mid-Atlantic region.
On March 18th, 5.5” hail was measured and reported near Smithville, TX. The next day, 4-5” hail hammered Cullman, AL. In a little town just 10 miles southeast of Cullman called Walter, a reporter for the Cullman Tribune, Craig Mann, collected one of the stones and preserved it in his freezer. The following day, the NWS measured the stone to be 5.38” which set the new state record for the largest hailstone in Alabama.
Two hail storms of 2018 exceeded damage costs over $1 billion each. June 19 in the Denver, CO metro area, baseball size hail pelted the citizens of the Centennial, CO suburb. Extensive property damage totaled nearly $2.2 billion. It became the second costliest hailstorm in U.S. history, sliding in just under the $2.5 billion hailstorm that hit Kansas, Missouri, and Illinois on April 10th, 2001.
The second billion-dollar hailstorm of 2018 also occurred in Colorado, this time in Colorado Springs on August 6th. Anyone who experienced or saw the scene of families running for shelter at the Cheyenne Mountain Zoo, via news reports and social media uploads, will likely never forget it. 14 people were injured as a result of being hit by hail and chaos, 8 of which were transported to hospitals immediately after the event.
The damages caused by this hail event were estimated at just over $1billion. So in only 2 hail events, Colorado experienced a loss of $3.2 billion.
Hail can happen anywhere
Five additional states experienced million dollar losses in 2018 due to hail greater than 4”. These events include: 4.5” hail that fell in South Dakota and 4” hail that fell in Kansas on June 29, 4” hail that fell in Nebraska and Kansas on May 1st, 4” hail that fell in Kansas on May 29, 4” hail that fell in Texas on May 25, 4” hail that fell in Michigan on June 30, and 4” hail that fell in Colorado on June 6.
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What to expect in 2019
Looking forward to 2019, how likely is it that these multi-million and even billion-dollar disasters will continue? Hail can happen anywhere at any time given the prime atmospheric conditions. There is no such thing as “Hail Season”.
Tech will help us see it coming
As a homeowner, your property is your most valuable asset. Predicting down to the street where hail is going to happen is still almost impossible. However, new technologies are working to get forecasting to a more superior level of accuracy. From a meteorological standpoint, there is no way of saying for sure where severe weather will happen and at what time, with certainty, more than a few days prior to the event. However, climatic data can give us clues as to what type of season we may be looking at.
The El Niño Southern Oscillation plays a huge role in the weather over the United States. Low-pressure systems are drawn further south and are fueled by the energy coming off of the warmer waters. The Polar Jet retreats further north and the Subtropical Jet becomes more dominant.
Typically, when we’re not in an El Niño year, we would expect our strongest low-pressure systems to come southward from Canada or the far Northwest Pacific coast. Over the life of the low-pressure system we would expect to see severe storms over the Great Plains, also known as Tornado Alley (Texas, Oklahoma, Kansas, Nebraska, and South Dakota), as well as Hoosier Alley (Kentucky, Illinois, Indiana and Ohio) and Dixie Alley (North Carolina, South Carolina, Georgia, Kentucky, Tennessee, Alabama, Missouri, Arkansas, Mississippi, Louisiana, and Texas).
However, during El Niño conditions, the Subtropical Jet carries most of the low-pressure systems across the southern half of the U.S. The southern states experience above-average rainfall and cooler than average temperatures. On the opposite end of the spectrum, the Midwest and Northern states often experience warmer than average temperatures and below-average precipitation. Concerning Severe Weather Perils, the southernmost states of the US will likely see above-average flooding and damaging winds, with occasional large hail and tornadoes.
From a historical standpoint, Texas generally gets hit hardest by El Niño averaging 140 tornadoes during El Niño years. Because of the rise in supercell activity in the south, large hail becomes a greater threat. The 2019 outlook for spring appears that hail will be a big concern for Texas because of an expected increase in supercell thunderstorms. In the summer of 2019, hail will likely be of concern for the High Plains region (southeastern Wyoming, southwestern South Dakota, western Nebraska, eastern Colorado, western Kansas, eastern New Mexico, western Oklahoma, and south of the Texas Panhandle) because of expected high instability.
This outlook can vary based on the sea surface temperatures of the Pacific Ocean but it represents a fair forecast based on current teleconnection data.
Hail and your property
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What you can do to protect your home
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